Hydrolysis Reaction Kinetics Of Dioxolane Compounds And New Process Design Of Reactive Distillation

In the production process of coal-based ethylene glycol(EG),Chemical Looping Technology is a potential and effective method for separating EG.Our group has done a lot of research on the reaction circulating solvent,which confirmed that during the production of coal-based EG,acetaldehyde as a chemical circulating solvent can achieve the effective separation of the azeotropic system of EG and 1,2-butanediol(1,2-BDO).However,the hydrolysis process of dioxolane compounds(the acetal product)are limited by the chemical balance,resulting in some bottleneck problems such as low conversion rate,large unreacted circulation,high energy consumption.Therefore,this article proposed a strategy of process strengthening using reactive distillation(RD)craft that focuses on the hydrolysis process of2-methyl-1,3-dioxolane(2MD)and 4-ethyl-2-methyl-1,3-dioxolane(4EMD),which are acetal products of EG,1,2-BDO and acetaldehyde.In order to simulate and design the hydrolysis RD process accurately,the kinetic data of the 2MD hydrolysis reaction was measured when the cation exchange resin was used as a catalyst.The effects of the catalyst particle size,stirring speed,reactive temperature,catalyst mass,reaction molar ratio and other factors on the reactive conversion rate were mainly determined.A quasi-homogeneous model was used to regress the reaction kinetic equation,the regression results were in good agreement with the experimental results.Finally,the 2MD hydrolysis kinetic equation was obtained.On this basis,according to the 4EMD hydrolysis reaction kinetics equations and the thermodynamic data of the 2MD and 4EMD hydrolysis systems,which were measured by our research group previously,the mathematical model of the 2MD hydrolysis reaction distillation process and the 4EMD hydrolysis reaction distillation process were established respectively.In the two RD process,the effects of various factors on the energy consumption of RD,the conversion rate of 2MD and 4EMD were analyzed respectively by the established model.The results show that the more optimized design got from the mathematical model of the 2MD hydrolysis RD process is: the total theoretical stages is 15(the top condenser is 1),and 6～8 are the reaction zones.Operating conditions: the feed flow rate of water is 280 kmol/hr,the feed flow rate of 2MD is 100 kmol/hr,the operating pressure is 0.2 atm,and the reflux ratio is 0.15.At this time,the RD column achieved a good result,the energy consumption of the reboiler was 4047.9 k W,and the conversion rate of 2MD reached99.9% with as little energy as possible.On the other hand,the simulation results of the 4EMD hydrolysis RD process show that the hydrolysis process has achieved a good result,the more optimized parameters of RD are as follows: the total theoretical stages is 15(the top condenser is 1),3～12 are the reaction zones;operating conditions:the water feed flow rate is 125 kmol/hr,the 2MD feed flow rate is 50 kmol/hr,operating pressure is 2.0 atm,reflux ratio is 1.2.At this time,the energy consumption of the reboiler is 4129.6 k W,and the conversion rate of 4EMD has reached 99.9%.